US8147173B2 - Adapter for operating a keyhole saw on a driving machine - Google Patents

Abstract

An adapter for operating a keyhole saw (10) on a driving machine includes a driving section (17; 117) for absorbing torque and a threaded section (18; 118) screwed into a threaded hole (20) in the keyhole saw (10). A driving segment (16; 116) is offset radially relative to the adapter axis and is inserted in a form-fit manner into a receiving hole (21) present in the keyhole saw (10). The driving segment (16; 116) is located in an axially extending manner on the end of a driving element (12; 112) which includes the driving element section (17; 117). The threaded section (17; 117) is formed on a threaded mandrel (13; 113) which is situated in the driving element (12; 112) and is non-detachably connected thereto. The threaded mandrel (13; 113) is held in the driving element (12; 112) in a rotatable manner to be axially displaceable to a limited extent.

Description

CROSS-REFERENCE

The invention described and claimed hereinbelow is also described in PCT/EP2008/053315, filed on Mar. 19, 2008 andDE 10 2007 022 186.1, filed on May 11, 2007. This German Patent Application, whose subject matter is incorporated here by reference, provides the basis for a claim of priority of invention under 35 U.S.C. 119 (a)-(d).

BACKGROUND OF THE INVENTION

The present invention is directed to an adapter for operating a keyhole saw on a driving machine, in particular an electric hand-held drill.

A known part of an adapter which forms a “power change system” for receiving a keyhole saw (EP 1 193 014 A1 and DE 601 04 177 T2) has the shape of a hollow hexagonal prism which is provided, at one end, with a threaded section around its circumference, and, close to the other end, it is provided with a circumferential, concave detent groove. The threaded section is screwed into a central threaded hole of the keyhole saw, and the adapter—having the keyhole saw attached thereto—is slid via its hexagonal prism into a drive sleeve having an inner, hexagonal sleeve wall until a detent ball which is held in a radial bore in the sleeve wall drops into the detent groove and holds the adapter in a non-displaceable manner. A sliding sleeve which is displaceable against the restoring force of a compression spring is situated on the drive sleeve for locking and unlocking the adapter. In the locking position, the sliding sleeve closes the radial bore to the outside, thereby blocking the detent ball which has dropped into the detent groove of the adapter and preventing it from being displaced in the radial direction. In the unlocking position, which the sliding sleeve assumes after following a displacement path against the restoring force of the compression spring, the radial bore is congruent with a recess in the inner wall of the sliding sleeve, thereby allowing the detent ball to escape radially outwardly when one of the groove flanks of the detent groove in the adapter strikes the detent ball when the adapter is pulled out of the drive sleeve, or when the adapter is slid into the drive sleeve. The drive sleeve includes a hexagonal receiving shank which is placed in the chuck of an electric hand-held power tool. When drilling is performed using the keyhole saw, a “pilot bit” is typically used to guide the keyhole saw in an exact manner. The pilot bit includes a hexagonal shank and a circumferential detent groove in the hexagonal shank, and it is held in a bit-connecting piece in a non-rotatable manner via the hexagonal shank and via a detent ball which drops into the detent groove in the hexagonal shank of the pilot bit, the detent ball being held in an axially non-displaceable manner in the bit-connecting piece in a radial bore. The bit-connecting piece is accommodated in the adapter and extends via a hexagonal segment part into the similarly formed hollow interior of the shank of the drive sleeve.

Given large diameters of the keyhole saw, to prevent the thread from stripping when high torques are transferred, two diametrically opposed driving holes are provided in the keyhole saw, and two axially extending driving pegs which extend into the driving holes are situated on the end face—which faces the keyhole saw—of the drive sleeve. The transfer of torque from the electric hand-held power tool via the drive sleeve to the keyhole saw therefore takes place via the driving pegs and the driving holes, and the load is relieved from the threaded connection between the keyhole saw and the adapter. The connection between the keyhole saw and the electric hand-held power tool is established by screwing the adapter via its threaded section tightly into the threaded hole of the keyhole saw, and then inserting the adapter into the drive sleeve until the driving pegs strike the keyhole saw. After the driving pegs are aligned with the driving holes, the adapter is slid completely into the drive sleeve, and the driving pegs enter the driving holes; the sliding sleeve must be pushed back against the force of the restoring spring until the detent groove of the adapter moves under the detent ball, then the detent ball drops into the detent groove. After the sliding sleeve is released, the restoring spring forces the sliding sleeve back, and the adapter is locked in place in the drive sleeve in an axially non-displaceable manner. After the pilot bit is inserted, the drive sleeve is inserted via its hexagonal shank into the chuck of the electric hand-held drill.

In the case of a known adapter, which is of a “standard design” and may be inserted directly into the chuck of an electric hand-held power tool, the driving pegs and threaded section are also situated on two separate components which are placed on the keyhole saw individually, while being joined together, and are then detachably connected to one another. The hollow component which includes the threaded section, into which the pilot bit is also inserted, includes a hexagonal clamping shank which is inserted into the chuck of the electric hand-held power tool, while the component on which the driving pegs are mounted is attached via a radial screw to the threaded section and the component on which the clamping shank is mounted.

SUMMARY OF THE INVENTION

The adapter according to the present invention for receiving a keyhole saw having the features mentioned in claim1 has the advantage that the adapter is a single piece, and it is possible to perform these two procedures in one working step: via rotation, align the driving pegs which are located on the adapter with the driving holes which are present in the keyhole saw after the threaded mandrel is screwed into the threaded hole, then insert the driving pegs into the driving holes as required, using a linear motion; a play-free connection is then established between the keyhole saw and the adapter. In contrast to the known adapters, in the case of which the threaded section and the driving pegs are distributed on components which are separable from one another, are installed separately with the keyhole saw and must then be connected to one another, in this case, the threaded section and the driving pegs are combined to form one assembly and are not separable from one another, thereby ensuring that none of the components may become lost.

When the driving section is designed accordingly, the adapter according to the present invention may be clamped directly in the chuck of an electric hand-held power tool, and it may be clamped directly in the chuck of an electric hand-held power tool using the known, above-described drive sleeve of the “power change system”.

Via the measures mentioned in the further claims, advantageous developments and improvements of the adapter described in claim1 are made possible.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is described in greater detail in the description that follows, with reference to embodiments depicted in the drawings.

FIG. 1 shows a side view of a keyhole saw and an adapter for receiving the keyhole saw,

FIG. 2 shows an exploded view of the adapter inFIG. 1,

FIG. 3 shows a longitudinal sectional view of a coupling part of a “power change system” with the adapter shown inFIGS. 1 and 2 installed,

FIG. 4 shows a longitudinal sectional view of an adapter according to a second embodiment,

FIG. 5 shows a perspective view of the adapter in the direction of arrow V inFIG. 4.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Adapter11 for receiving akeyhole saw10, which is shown in an exploded view and a side view inFIGS. 1 and 2, is designed to be part of a “power change system” which may be operated in various configurations using an electric hand-held power tool, whileadapter111 shown inFIGS. 4 and 5 is designed to be inserted into the chuck of an electric hand-held power tool.

Adapters11 and111 both include adriving element12 and112 and a hollow cylindrical threadedmandrel13 and113 which is situated in drivingelement12 and112 in a rotatable and axially displaceable manner.Driving element12 and112 includes adriving element body14 and114, and a drivingflange15 and115 which extends thereon as a single piece, the flange surface—that faces away from drivingelement body14 and114—of which forms a mating surface for keyhole saw10. Two drivingpegs16 and116 are situated diametrically to the driving axis on drivingflange15 and115, and they extend past the exposed flange surface—which forms the mating surface—parallel to the driving axis. Drivingpegs16 and116 are designed as single pieces with drivingflange15 and115, as shown in the top part ofFIGS. 3 and 4, or they are inserted as separate components into relatedaxial bores19 and119, and are pressed or staked therein, as illustrated in the bottom part ofFIGS. 3 and 4.Driving element body14 and114 includes adriving section17 and117 via which drivingelement12 and112 absorbs a torque which is derived from the electric hand-held power tool.

Threadedmandrel13 and113, which is rotatably situated in drivingelement12 and112, extends on the flange side ofdriving element12 and112 out of drivingelement12 and112, and it is provided in the end region with a threadedsection18 and118 which is screwed into a central threadedhole20 present in keyhole saw10. Two diametrically opposed receivingholes21—into which drivingpegs16 and116 ofdriving element12 and112 may enter—are provided in keyhole saw10 at the same radial distance from one another that exists between drivingpegs16 and drivingelement body axis14. The displacement path of threadedmandrel13 and113 is limited by two axiallyinterspaced stops22 and122 on threadedmandrel13 and113, and by twocounter-stops23 and123—which interact withstops22 and122—on drivingelement12 and112.Stops22 and122, andcounter-stops23 and123 are situated such that the displacement path of threadedmandrel13 and113 in drivingelement14 and114 is designed to be so great that the end—on which threadedsection18 and118 is provided—of threadedmandrel13 and113 may be pulled back behind the exposed front ends of drivingpegs16 and116, so that drivingpegs16 and116 may be inserted into receivingholes21 in keyhole saw10 before threadedsection18 and118 is screwed into threadedhole20 of keyhole saw10. Acentral recess50 and150 which leads into the flange surface which is used as the mating surface forkeyhole saw10 is provided in drivingflange15 and115. Threadedmandrel13 and113 includes, on the end of its threadedsection18 and118, a circumferentialradial collar51 and151 which extends intorecess50 and150.Radial collar51 and151 forms stop22 and122, and the base ofrecess50 and150forms counter-stop23 and123 which interacts withstop22 and122 in order to limit the displacement path of threadedmandrel13 and113 indriving element12 and112.

In the case ofadapter11 depicted inFIGS. 1 through 3,driving section17 is designed as anexternal hexagon24 for insertion, in a form-fit manner, into acoupling piece25—which is also referred to as a base mechanism—of a power change system.Coupling part25 is known, and it is described in detail in EP 1 193 014 A1 which is documented above, and will therefore be described only briefly below.

Coupling part25 includes adrive sleeve26 which includes ahexagonal shank27 for insertion into the chuck of an electric hand-held power tool, and a slidingsleeve28 which may be displaced ondrive sleeve26 against the force of acompression spring29.Coupling part25 also includes a bit-connectingpiece30 which is inserted inadapter11 and extends via ahexagonal shank31 into a similarly designed hexagonal hollow cavity inhexagonal shank27 ofdrive sleeve26. Bit-connectingpiece30 includes acentral recess32, the interior wall of which has a hexagonal design, and a radially displaceabledetent ball33. Apilot bit34 for guiding keyhole saw10 using ahexagonal shank35 is inserted into bit-connectingpiece30, and it is locked in an axially non-displaceable manner via adetent ball33 which drops intodetent groove36 inhexagonal shank35.

The inner wall ofdrive sleeve26 is also hexagonal in design;adapter11 withouter hexagon24 on drivingelement12 is therefore held indrive sleeve26 in a form-fit manner in the direction of rotation. In order to holdadapter11 in an axially non-displaceable manner, adetent ball38 is held in a radially displaceable manner in aradial bore37 ofdrive sleeve26,detent ball38 extending radially outwardly from inner wall ofdrive sleeve38 and being secured against falling out ofradial bore37 by slidingsleeve28. Arecess39 which extends to the end of slidingsleeve28 is formed in the inner wall of slidingsleeve28. Aradial flange40 which is formed ondrive sleeve26 extends intorecess39. Acompression spring29 is situated inrecess39, and bears againstradial flange40 and against aring41 which is inserted on the end side inrecess39 and is attached to slidingsleeve28. When slidingsleeve28 is slid to the left as shown inFIG. 3, andcompression spring29 is compressed, a part ofrecess39 extends overdetent ball38 so thatdetent ball38 may move radially outwardly intorecess39, thereby enabling it to move behind the inner wall ofdrive sleeve26.

As shown inFIGS. 1 through 3, threadedmandrel13 which is accommodated in drivingelement12 extends via anend section42—which faces away from threadedsection18—beyond drivingelement body14. Aholding ring43 is attached, e.g. via pressing or shrink-fitting, onend section42, and aspring element44 designed as a snap ring having an axially-acting spring force is installed,spring element44 bearing against the end surface of drivingelement body14 and againstholding ring43.Holding ring43 includes, on its free end, anannular section45 which is knurled, and, on its end facingdriving element body14, it includes a hexagonalannular section46 which is matched toouter hexagon24 ofdriving element body14. A circumferential, concavedetent groove47 is situated betweenannular sections45,46, and is used, in combination withdetent ball38 ofdrive sleeve26 ofcoupling part25, to lockadapter11 incoupling part25. Two radial stops48 (FIG. 2) which extend axially outwardly are diametrically opposed on the end surface—which faces drivingelement body14—ofholding ring43,radial stops48 interacting with twocounter-stops49—which are situated on the end surface of drivingelement body14—in such a manner that radial stops48 andcounter-stops49 engage in one another—at the end of the procedure to screw threadedsection18 into central threadedhole20 of keyhole saw10—when the hexagon onannular section46 ofholding ring43 becomes aligned withouter hexagon24 of drivingelement body14.Spring element44 ensures that this orientation of holdingring43 and drivingelement body14 is retained during assembly.

In the embodiment shown inFIGS. 1 through 3, theother stop22 which is used to limit the displacement path of threadedmandrel13, is located on threadedmandrel13, and prevents threadedmandrel13 from falling out of drivingelement12, is formed by holdingring43 and theother counter-stop23 of drivingelement body14, which interacts withstop22.

To assemblekeyhole saw10 andadapter11,complete adapter11—as shown, assembled, in FIG.1—is placed onkeyhole saw10 in a manner such that driving pegs16enter receiving holes21 inkeyhole saw10. Threadedsection18 of threadedmandrel13 is then screwed into threadedhole20 ofkeyhole saw10; to do this, threadedmandrel13 is rotated manually using knurledannular section45.Spring element44 becomes increasingly loaded as threadedsection18 is screwed in further. When the end of the screw-in procedure has been reached, radial stops48 on holdingring43 bear againstcounter-stops49 on drivingelement body14, and hexagonalannular section46 of holdingring43 is simultaneously aligned withouter hexagon24 of drivingelement body14. Bit-connectingpiece30 withpilot bit34 inserted is now introduced into threadedmandrel13, andadapter11 is slid intodrive sleeve26. Slidingsleeve28 is thereby displaced manually to the left—as shown in FIG.3—untilrecess32 lies overdetent ball33.Entire adapter11 is slid inward untildetent ball33 drops intodetent groove47 in holdingring43. If slidingsleeve28 is now released, it is returned via the action ofcompression spring29 to its locking position shown inFIG. 3, in whichdetent ball33 extends intodetent groove47 in a radially non-displaceable manner and locksadapter11 indrive sleeve26 in an axially non-displaceable manner.

In the case ofadapter111 which is shown inFIGS. 4 and 5 and is clamped directly in the chuck of an electric hand-held power tool, drivingelement section117 on drivingelement body114 of drivingelement112 is formed by astub chuck152 which extends as a single piece on the end—which faces away from drivingelement flange115—of drivingelement body114. Drivingelement body114 includes a radiallycontinuous recess153, through which hollow threadedmandrel113 passes. A manually grippable rotation aid in the form of aknurled wheel154 is attached to threadedmandrel113 in the region ofrecess153. Viaknurled wheel154, threadedmandrel113 may be rotated in order to screw threadedsection118 into threadedhole20 ofkeyhole saw10. Bit-connectingpiece130 is inserted into threadedmandrel113 and extends viahexagonal shank131 into a correspondingblind hole155 instub chuck152, thereby being carried along in the direction of rotation in a form-fit manner. Bit-connectingpiece130 also includes arecess132 having a hexagonal inner wall for receiving the hexagonal shank of the pilot bit, as shown inFIG. 3.

Threadedmandrel113 includes, on its end which faces away from threadedsection118, anend section156 having a reduced inner diameter. Cylindrical bit-connectingpiece130 includes acylindrical section157 which has a reduced diameter and is inserted throughsection156 of threadedmandrel113. The radial shoulders which are formed at the transitions ofsections156 and157 form theother stop122 on threadedmandrel113 and counter-stop123—which interacts withstop122—on drivingelement112 to limit the axial displacement path of threadedmandrel113 in drivingelement112, thereby also preventing threadedmandrel113 from falling out of drivingelement112.Cylindrical section157 is much larger in its axial length than issection156 on threadedmandrel113, thereby ensuring that threadedmandrel113 may be displaced axially.

Claims (17)

What is claimed is:

1. An adapter for operating a keyhole saw (10) on a driving machine, in particular an electric hand-held drill, comprising a driving element section (17;117) for absorbing torque, and a threaded section (18;118) to be screwed into a threaded hole (20) in the keyhole saw (10), and comprising at least one driving segment (16;116) which is offset radially relative to the adapter axis, and which is inserted in a form-fit manner into at least one receiving hole (21) present in the keyhole saw (10),

wherein the at least one driving segment (16;116) is located in an axially extending manner on the end—which faces the keyhole saw (10)—of a driving element (12;112) which includes the driving element section (17;117), the threaded section (17;117) is formed on a threaded mandrel (13;113) which is situated in the driving element (12;112) and is non-detachably connected thereto, and the threaded mandrel (13;113) is held in the driving element (12;112) in a rotatable manner and such that it is axially displaceable to a limited extent,

wherein the driving element (12;112) includes a driving element body (14;114) on which the driving segment (16;116) is formed, and a driving flange (15;115) which extends the driving segment (16;116) as a single piece, and the flange surface of which that faces away from the driving element body (14;114) forms a mating surface for the keyhole saw (10),

wherein the threaded mandrel (13;113) extends, via the threaded section (18;118) and on the flange-side end of the driving element (12;112), beyond the driving element (12;112); and the displacement path of the threaded mandrel (13;113) in the driving element (12;112) is designed to be at least so great that the end—which faces away from the flange-side end of the driving element (12;112)—of the threaded section (18;118) may be slid back behind the exposed front end of the driving segment (16;116).

2. The adapter as recited inclaim 1, wherein two driving segments (16;116) which extend past the mating surface parallel to the driving axis are situated in a diametrically opposed manner on the driving flange (15;115).

3. The adapter as recited inclaim 2, wherein the driving segments (16;116) are inserted into flange holes (19;119) and are held there via pressing.

4. The adapter as recited inclaim 2, wherein the driving segments (16;116) are designed as single pieces with the driving flange (15;115).

5. An adapter for operating a keyhole saw (10) on a driving machine, in particular an electric hand-held drill, comprising a driving element section (17;117) for absorbing torque, and a threaded section (18;118) to be screwed into a threaded hole (20) in the keyhole saw (10), and comprising at least one driving segment (16;116) which is offset radially relative to the adapter axis, and which is inserted in a form-fit manner into at least one receiving hole (21) present in the keyhole saw (10),

wherein the at least one driving segment (16;116) is located in an axially extending manner on the end—which faces the keyhole saw (10)—of a driving element (12;112) which includes the driving element section (17;117), the threaded section (17;117) is formed on a threaded mandrel (13;113) which is situated in the driving element (12;112) and is non-detachably connected thereto, and the threaded mandrel (13;113) is held in the driving element (12;112) in a rotatable manner and such that it is axially displaceable to a limited extent,

wherein the driving element (12;112) includes a driving element body (14;114) on which the driving segment (16;116) is formed, and a driving flange (15;115) which extends the driving segment (16;116) as a single piece, and the flange surface of which that faces away from the driving element body (14;114) forms a mating surface for the keyhole saw (10),

wherein a stub chuck (152) which forms the driving element section (117) extends driving element body (114) as a single piece on its end facing away from the driving flange (115), and wherein the driving element body (114) includes a radially continuous recess (153) through which the threaded mandrel (113) extends axially, and a grippable rotation aid, in the form of a knurled wheel (154), is attached to the threaded mandrel (113) in the region of the recess (153).

6. The adapter as recited inclaim 1, wherein the displacement path of the threaded mandrel (13;113) is limited by axially interspaced stops (22;122) on the threaded mandrel (13;113), and by counter-stops (23;123) which are located on the driving element (12;112) and interact with the stops (22;122).

7. The adapter as recited inclaim 2, wherein the driving element body (14) includes an outer hexagon (24) which forms the driving element section (17) and which is to be inserted, in a form-fit manner, into a coupling part (25) which may be inserted into the driving machine.

8. The adapter as recited inclaim 7, wherein the threaded mandrel (13) which is located inside the driving element (12) extends—via an end section (42) which faces away from the threaded section (13)—beyond the driving element (12), and a holding ring (43) is attached to the projecting end section (42), having been shrunk-fit thereon, and the holding ring (43) forms a stop (22) for limiting the displacement path of the threaded mandrel (13).

9. The adapter as recited inclaim 8, wherein the holding ring (43) includes a knurled annular section (45).

10. The adapter as recited inclaim 8, wherein the holding ring (43) includes a concave detent groove (47) which is formed in the outer surface of the ring, and which is designed to accommodate a locking element, in the form of a detent ball (38), which is held in the coupling part (25).

11. The adapter as recited inclaim 10, wherein the holding ring (43) includes a hexagonal annular section (46) which is matched to the outer hexagon (24) of the driving element section (17) on the driving element body (14).

12. The adapter as recited inclaim 11, wherein the detent groove (47) is located between the two annular sections (45,46).

13. The adapter as recited inclaim 7, wherein a spring element (44), in the form of a snap ring, bears via axially directed spring force between the holding ring (43) and the end face of the driving element body which faces the holding ring (43).

14. The adapter as recited inclaim 13, wherein an axially extending radial stop (48) is located on the holding ring (43), and a counter-stop (49) is located on the driving element (12) and extends axially away from its end face, the radial stop (48) and counter-stop (49) being designed such that they abut one another at the end of the procedure of screwing the threaded section (18) into the threaded hole (20) formed in the side of the keyhole saw when the outer hexagon (24) on the driving element body (14) and the hexagonal annular section (46) on the holding ring (43) are aligned with one another.

15. The adapter as recited inclaim 2, wherein a stub chuck (152) which forms the driving element section (117) extends driving element body (114) as a single piece on its end facing away from the driving flange (115).

16. The adapter as recited inclaim 15, wherein the driving element body (114) includes a radially continuous recess (153) through which the threaded mandrel (113) extends axially, and a grippable rotation aid, in the form of a knurled wheel (154), is attached to the threaded mandrel (113) in the region of the recess (153).

17. The adapter recited inclaim 1, wherein the threaded mandrel (13;113) is hollow-cylindrical in design, and a bit-connecting piece (30;130) which is used to insert a pilot bit (34) is situated in the threaded mandrel (13;113).

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